The present invention relates generally to apparatus and methods for treating vascular conditions, and more specifically, by treating the vascular conditions by restoring patency to the vessel while reducing the likelihood that emboli become dislodged into the bloodstream.
Atherosclerosis and other occlusive diseases are prevalent among a significant portion of the population. In such diseases, atherosclerotic plaque forms within the walls of the vessel and blocks or restricts blood flow through the vessel. Atherosclerosis commonly affects the coronary arteries, the aorta, the iliofemoral arteries and the carotid arteries. Several serious conditions may result from the restricted blood flow.
Various procedures are known for treating stenoses in the arterial vasculature, such as the use of atherectomy devices, balloon angioplasty and stenting. During an atherectomy procedure, vascular plaque may be removed by inserting a catheter having a rotating cutting blade into the vessel and using the blade to shave away the plaque. During a balloon angioplasty procedure, a catheter having a deflated balloon attached thereto is positioned across a constricting lesion, and the balloon is then inflated to widen the lumen to partially or fully restore patency to the vessel.
Stenting involves the insertion of a usually tubular member into a vessel, and may be used alone or in conjunction with an angioplasty procedure. Stents may be self-expanding or balloon expandable. Self-expanding stents typically are delivered into a vessel within a delivery sheath, which constrains the stent prior to deployment. When the delivery sheath is retracted, the stent is allowed to radially expand to its predetermined shape. If the stent is balloon expandable, the stent typically is loaded onto a balloon of a catheter, inserted into a vessel, and the balloon is inflated to radially expand the stent.
One problem frequently encountered with atherectomy, angioplasty and stenting procedures is that pieces of plaque are often dislodged from the stenosis. Such pieces of plaque, referred to as emboli, may flow away from the stenosis into other areas of the vasculature and may be difficult to retrieve. Serious complications, such as heart attack and stroke, may occur where the emboli travel into the coronary, carotid or other arteries and vessels.
Several techniques exist for retrieving emboli during a medical procedure, such as deploying a filter within the vasculature distal to the stenosis prior to treatment of the stenosis to capture free-floating particles. Such embolic filtration devices may comprise a mesh or net material coupled to a plurality of expandable struts. The struts deploy radially outward into engagement with the vessel wall, and the net is configured to entrap emboli dislodged while the stenosis is treated.
Various problems exist with the use of such embolic filtration devices. For example, the net may not fully capture all embolic particles, especially relatively small fragments that may escape through the net. Further, when relatively large embolic particles are captured within the net and the filter device is retracted into the delivery system, e.g., a catheter, such larger particles may be difficult to retract within the confines of the delivery system.
In view of the foregoing, there is a need for apparatus and methods that effectively treat a vascular condition by restoring patency to the vessel while reducing the likelihood that emboli become dislodged into the bloodstream.